OQL LEAGUE
OQL LEAGUE 1.1 Introduction In this chapter, we describe an object query language named OQL, which supports the ODMG data model. It is complete and simple. It deals with complex objects without privileging the set construct and the select-from-where clause. We first describe the design principles of the language in Section 1.2, then we introduce in the next sections the main features of OQL. We explain the input and result of a query in Section 1.3. Section 1.4 deals with object identity. Section 1.5 presents the path expressions. In Section 1.6, we show how OQL can invoke operations and Section 1.7 describes how polymorphism is managed by OQL. Section 1.8 concludes this part of the presentation of the main concepts by exemplifying the property of operators composition. Finally, a formal and complete definition of the language is given in Section 1.9. For each feature of the language, we give the syntax, its semantics, and an example. Alternate syntax for some features are...